Add a button to manually trigger synchronization #86

Description

Currently, synchronization happens automatically, but there is no way for users to trigger it on demand. To improve user control and flexibility, add a button that allows manual synchronization.

Acceptance Criteria:

• A visible button is added to the UI (if known, specify the location).
• When clicked, the button initiates the synchronization process.
• Provide user feedback (e.g., loading spinner or success message) during and after synchronization.
• Ensure proper error handling if synchronization fails.